Birgid Schlindwein's

Hypermedia Glossary Of Genetic Terms

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Genetic variation between individuals in DNA fragment sizes resulting from a difference in DNA sequence that affects the recognition sequence for restriction enzymes when cut by specific restriction enzymes. When DNA is digested by a particular enzyme the fragment sizes will differ depending on the presence or absence of the proper recognition sequence for the enzyme. Polymorphic sequences that result in RFLPs are used as markers on both physical maps and genetic linkage maps. RFLPs are usually caused by mutation at a cutting site.

Related Terms:

Deoxyribonucleic acid
(DNA)

The molecule that encodes genetic information. DNA is a double-stranded molecule held together by weak bonds between base pairs of nucleotides. The four nucleotides in DNA contain the bases: adenine (A), guanine (G), cytosine (C), and thymine (T). In nature, base pairs form only between A and T and between G and C; thus the base sequence of each single strand can be deduced from that of its partner.

Difference in DNAsequence among individuals. Applied to many situations ranging from genetic traits or disorders in a population to the variation in the sequence of DNA or proteins. Genetic variations occurring in more than 1% of a population would be considered useful polymorphisms for genetic linkage analysis. Compare mutation.

Marker

An identifiable physical location on a chromosome (e.g., restriction enzyme cutting site, gene, minisatellite, microsatellite) whose inheritance can be monitored. Markers can be expressed regions of DNA (genes) or some segment of DNA with no known coding function but whose pattern of inheritance can be determined. See RFLP, restriction fragment length polymorphism.

A specific nucleotidesequence of DNA at which a particular restriction enzyme cuts the DNA. Some sites occur frequently in DNA (e.g., every several hundred base pairs), others much less frequently (rare-cutter; e.g., every 10,000 base pairs).